SDDM: how to make Wayland the default session?

I’m running into an sddm-greeter crash and would like to see, if a Wayland session helps.

I added this to my configuration.nix:

services.xserver.desktopManager.plasma5.runUsingSystemd = true;
services.xserver.displayManager.sessionPackages = [
  (pkgs.plasma-workspace.overrideAttrs
    (old: { passthru.providedSessions = [ "plasmawayland" ]; }))
];

How can I make Wayland the default session, so I will be able to test? The way I see it, overrideAttrs should replace the passthru.providedSessions list, but I am still getting autologged into an X11 session and then can’t log out due to the sddm-greeter crash. I can launch a Wayland session from a virtual terminal with dbus-run-session startplasma-wayland just fine.

Answer is
services.xserver.displayManager.defaultSession = "plasmawayland";
Although autologin is now broken, but I will start another thread.

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